Thallium-195

Properties and data of the isotope ¹⁹⁵Tl.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

See also: List of individual Thallium isotopes (and general data sources).

General data

Name of the isotope:Thallium-195; Tl-195Symbol:¹⁹⁵Tl or 19581TlMass number A:195 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:114Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.4074074074074 (= neutron-proton ratio)Neutron excess (N-Z):33Isotopic mass:194.969774(12) u (atomic weight of Thallium-195)Nuclide mass:194.925344 u (calculated nuclear mass without electrons)Mass excess:-28.15534 MeVMass defect:1.651854016 u (per nucleus)Nuclear binding energy:1538.69210478 MeV (per nucleus)
7.89072874 MeV (average binding energy per nucleon)Separation energy:S_N = 9.289(18) MeV (first neutron)
S_P = 3.260(11) MeV (first proton)Half-life:1.16(5) hDecay constant λ:0.00016598352024903 s^-1Specific activity α:5.152454326638 × 10⁺¹⁷ Bq g^-1
13925552.234157 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Magnetic dipole moment:μ(μ_N) = + 1.58(4)Nuclear g-factor:g_l = 3.16Charge radius:5.4325(39) femtometer fmYear of discovery:1955

Radioactive Decay

Half-life T_½ = 1.16(5) h (hours) respectively 4.176 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁹⁵Hg	100 %	2.858(26) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁹⁹Bi, ¹⁹⁵Pb.

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^195mTl	482.63(17) keV	3.6(4) s	9/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 114) and isobaric (same nucleon number A = 195) with Thallium-195. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 114	Isobar A = 195
70	¹⁸⁴Yb
71	¹⁸⁵Lu
72	¹⁸⁶Hf
73	¹⁸⁷Ta
74	¹⁸⁸W	¹⁹⁵W
75	¹⁸⁹Re	¹⁹⁵Re
76	¹⁹⁰Os	¹⁹⁵Os
77	¹⁹¹Ir	¹⁹⁵Ir
78	¹⁹²Pt	¹⁹⁵Pt
79	¹⁹³Au	¹⁹⁵Au
80	¹⁹⁴Hg	¹⁹⁵Hg
81	¹⁹⁵Tl	¹⁹⁵Tl
82	¹⁹⁶Pb	¹⁹⁵Pb
83	¹⁹⁷Bi	¹⁹⁵Bi
84	¹⁹⁸Po	¹⁹⁵Po
85	¹⁹⁹At	¹⁹⁵At
86	²⁰⁰Rn	¹⁹⁵Rn
87	²⁰¹Fr
88	²⁰²Ra
89	²⁰³Ac